IndiGo, the low-cost carrier and frequency and capacity leader, and Air India, the full-service carrier, were the two ends of the spectrum. Within days, that is changing with Air India assuming the lead on the capacity and frequency front and IndiGo starting dual-class service.

Mount Lewotobi Laki Laki, situated on a remote Indonesian island, erupted earlier this month, creating ash clouds that pose potential hazards for aircraft. Given the unpredictable nature of volcanic ash dispersal,